Process for producing aluminum and aluminum alloys



ateuted Aug. 12, l3$

arise TUBE E'QBERT HAGLUND, U1 STGG'KHOLH, SWEDEN, ASSIGNQB TO IHTERNATIGNAL EATENT GOR?0RATION, A GQBPORATION GE MARYLAND PQESS F03 ERGDUCING ALUMINUM AND ,ALUEKXHUM ALLGYS We Drawing. Application filed ()ctober 19, 1925, aerial No. 83,547, and in Sweden November 15, 13%.

This invention has for its object a process for producing aluminum and aluminum alloys by electrolysis of a molten electrolyte containing aluminum oxide, and refers to such processes in which a raw material containing A1 0 in a crystallized or crystalline state is supplied to the electrolytic bath. In

such processes a hard crust of solidified material is formed on the top of the electrolytic bath on account of the high specific gravity of such oxide.

According to the present invention the extent of the said crust formation is reduced by using amorphous aluminum oxide together with the crystallized or crystalline aluminum oxide. The percentage of amorphous aluminum oxide may vary Within very wide limits. A good result is for instance reached by keeping the amorphous oxide 10-40% of the total quantity of aluminum oxide.

The two kinds of oxide may either be mixed before the charging, or they may be conveyed separately to the electrolytic bath. in the latter case the amorphous oxide should suitably he supplied immediately after the crystallized or crystalline oxide, in order to form a layer of amorphous oxide covering the latter.

With crystallized or crystalline aluminum oxide I mean an aluminum oxide of hi h specific gravity, and in the first place oxi es formed by crystallization out of a melt, such as corun um, produced for instance by the process described in my co-pending U. S.

patgnt application Ser. 579,964, of August 5, 192

With amorphous aluminum omde I mean an oxide with a lower s ecific ayity, for instance such'as receive by cacinatlon of hydrate or salts of aluminum.

I claim:

1. In a process of producin metallic aluminum h electrolysis of a mo ten hath containing a uminum oxide, the method of adding aluminum oxide to the oath, compriein first adding c stallized aluminum oxide an thereupon a ding amorphous aluminum omge as a layer covering the crystallized cm a.

lized aluminum oxide and amorphous alu minum oxide, the quantity of said crystallized aluminum oxide being in excess of the quantity of added amorphous aluminum oxide.

In witness "whereof I have hereunto set my hand.

TUBE ROBERT HAGLUND. 

